PSR 0 自动加载 「已废弃」
此规范已被弃用 - 此规范已于 2014 年 10 月 21 日被标记为弃用,目前最新的替代规范为 PSR-4
本文是为自动加载器 ( autoloader ) 实现通用自动加载,所需要遵循的编码规范
规范说明
-
一个标准的命名空间 ( namespace ) 和 类 ( class ) 名称的定义必须符合以下结构:
\<Vendor Name>\(<Namespace>\)*<Class Name>
-
每一个命名空间都必须要使用 组织名 (
Vendor Name
) 作为顶级命名空间 -
如果需要的话,每一个命名空间下可以拥有多个子命名空间
-
当根据完整的命名空间加载文件时,每个命名空间之间的分隔符都会转换为常量
DIRECTORY_SEPARATOR
DIRECTORY_SEPARATOR 是 PHP 内置的,跟操作系统相关的目录分隔符
1. Unix 系统上是/
2. Window 系统上是\\
-
类名称中的每个下划线 (
_
) 都会被转换成常量DIRECTORY_SEPARATOR
。 下划线 (_
) 在命名空间中没有任何特殊含义 -
使用完整的命名空间名和类名加载一个文件时,要求自动添加
.php
作为文件扩展名 -
组织名称 ( Vendor Name )、命名空间( Namespace ) 以及类的名称( Class Name ) 可由任意大小写字母组成
范例
-
\Doctrine\Common\IsolatedClassLoader
=>/path/to/project/lib/vendor/Doctrine/Common/IsolatedClassLoader.php
-
\Symfony\Core\Request
=>/path/to/project/lib/vendor/Symfony/Core/Request.php
-
\Zend\Acl
=>/path/to/project/lib/vendor/Zend/Acl.php
-
\Zend\Mail\Message
=>/path/to/project/lib/vendor/Zend/Mail/Message.php
命名空间以及类名称中的下划线
-
\namespace\package\Class_Name
=>/path/to/project/lib/vendor/namespace/package/Class/Name.php
-
\namespace\package_name\Class_Name
=>/path/to/project/lib/vendor/namespace/package_name/Class/Name.php
以上是使用通用自动加载必须遵循的最低规范标准
可通过下面的示例函数 SplClassLoader
载入 PHP 5.3 的类文件,来验证你所写的命名空间以及类是否符合以上规范
标准实现范例
下面的函数 autoload($className)
为本规范的一个简单实现
<?php function autoload($className) { $className = ltrim($className, '\\'); $fileName = ''; $namespace = ''; if ($lastNsPos = strrpos($className, '\\')) { $namespace = substr($className, 0, $lastNsPos); $className = substr($className, $lastNsPos + 1); $fileName = str_replace('\\', DIRECTORY_SEPARATOR, $namespace) . DIRECTORY_SEPARATOR; } $fileName .= str_replace('_', DIRECTORY_SEPARATOR, $className) . '.php'; require $fileName; } spl_autoload_register('autoload');
类 SplClassLoader
下面的是类 SplClassLoader
的一种简单实现
如果你遵循了以上规范,可以把它用来载入你的类文件
这也是目前 PHP 5.3 建议的类文件载入方式
<?php /* * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. * * This software consists of voluntary contributions made by many individuals * and is licensed under the MIT license. For more information, see * <http://www.doctrine-project.org>. */ /** * SplClassLoader implementation that implements the technical interoperability * standards for PHP 5.3 namespaces and class names. * * http://groups.google.com/group/php-standards/web/psr-0-final-proposal?pli=1 * * // Example which loads classes for the Doctrine Common package in the * // Doctrine\Common namespace. * $classLoader = new SplClassLoader('Doctrine\Common', '/path/to/doctrine'); * $classLoader->register(); * * @license http://www.opensource.org/licenses/mit-license.html MIT License * @author Jonathan H. Wage <jonwage@gmail.com> * @author Roman S. Borschel <roman@code-factory.org> * @author Matthew Weier O'Phinney <matthew@zend.com> * @author Kris Wallsmith <kris.wallsmith@gmail.com> * @author Fabien Potencier <fabien.potencier@symfony-project.org> */ class SplClassLoader { private $_fileExtension = '.php'; private $_namespace; private $_includePath; private $_namespaceSeparator = '\\'; /** * Creates a new <tt>SplClassLoader</tt> that loads classes of the * specified namespace. * * @param string $ns The namespace to use. */ public function __construct($ns = null, $includePath = null) { $this->_namespace = $ns; $this->_includePath = $includePath; } /** * Sets the namespace separator used by classes in the namespace of this class loader. * * @param string $sep The separator to use. */ public function setNamespaceSeparator($sep) { $this->_namespaceSeparator = $sep; } /** * Gets the namespace seperator used by classes in the namespace of this class loader. * * @return void */ public function getNamespaceSeparator() { return $this->_namespaceSeparator; } /** * Sets the base include path for all class files in the namespace of this class loader. * * @param string $includePath */ public function setIncludePath($includePath) { $this->_includePath = $includePath; } /** * Gets the base include path for all class files in the namespace of this class loader. * * @return string $includePath */ public function getIncludePath() { return $this->_includePath; } /** * Sets the file extension of class files in the namespace of this class loader. * * @param string $fileExtension */ public function setFileExtension($fileExtension) { $this->_fileExtension = $fileExtension; } /** * Gets the file extension of class files in the namespace of this class loader. * * @return string $fileExtension */ public function getFileExtension() { return $this->_fileExtension; } /** * Installs this class loader on the SPL autoload stack. */ public function register() { spl_autoload_register(array($this, 'loadClass')); } /** * Uninstalls this class loader from the SPL autoloader stack. */ public function unregister() { spl_autoload_unregister(array($this, 'loadClass')); } /** * Loads the given class or interface. * * @param string $className The name of the class to load. * @return void */ public function loadClass($className) { if (null === $this->_namespace || $this->_namespace.$this->_namespaceSeparator === substr($className, 0, strlen($this->_namespace.$this->_namespaceSeparator))) { $fileName = ''; $namespace = ''; if (false !== ($lastNsPos = strripos($className, $this->_namespaceSeparator))) { $namespace = substr($className, 0, $lastNsPos); $className = substr($className, $lastNsPos + 1); $fileName = str_replace($this->_namespaceSeparator, DIRECTORY_SEPARATOR, $namespace) . DIRECTORY_SEPARATOR; } $fileName .= str_replace('_', DIRECTORY_SEPARATOR, $className) . $this->_fileExtension; require ($this->_includePath !== null ? $this->_includePath . DIRECTORY_SEPARATOR : '') . $fileName; } } }